Vat dyeing process and composition



UNTED Patented Jan. 19, 1937 2,067,928 VAT DYEING raocsss AND COMPOSITION Jean G. Kern, Hamburg, N. Y., assignor to National Aniline & Chemical Company, Inc., New York, N. Y., a corporation of New York No Drawing. Application April 8, 1935, Serial No.

- 15,261. In Japan September 3, 1934 27 Claims.

This invention relates to the art of dyeing and to dyeing compositions and their application to textile fibers. It relates especially to a new class of assistants for the dyeing of textile fibers and especially those of the vegetable type such as cotton, regenerated cellulose and the like, with vat dyes by a process in which a leuco compound of a vat dye is formed by the reduction of a vat dye in the presence of the fiber to be dyed, as

for example a printing process or a pad-jig dyeing process.

As is well known, vat dyes are solid substances which are insoluble in water. In order to render them useful in the dyeing of textile fibers 5 they are converted to a water soluble form, in which form they are taken up by the fiber, and then the fiber is subjected to an oxidizing, or fixing treatment whereby the vat dyestufi is again rendered insoluble. One general method'of application of vat dyes to the dyeing of textile fibers involves application of the dye in the unreduced form to the material to be dyed, subjecting the resulting material to a reducing treatment whereby the dye is converted to the soluble form inthe presence of the fiber and is taken up by the fiber, and then subjectingit to oxidation and/or other finishing treatments to fix the dye on the fiber and complete the finishing of the material. In dyeing with vat dyes by this general method one of two procedures is usually followed, it depending upon whether the textile material is to be dyed a uniform or so-called solid color, or is to be dyed in accordance with a pattern or design in one or more colors. If

the material is to be dyed a solid color, the socalled "pigment padding or pad-jig" process may be employed. If the material is to be dyed in accordance with a pattern or design, the so-- called printing process is generally utilized.

40 The pad-jig process of dyeing with vat dyes.

generally involves passing the textile material to be dyed through an aqueous suspension or socalled padding bath containing the unreduced vat dye in finely divided form suspended in a suitable suspension medium (such as water, which may or may .not also contain a gum or thickener and other substances, such as an assistant, sodium sulfide, disodium phosphate, etc.) whereby the fiber mechanically picks up the particles of insoluble dye; subsequently.working the textile material, having the particles of dye mechanically attached thereto, in a reducing bath whereby the dye is reduced to the soluble form and is taken up (absorbed and/or adsorbed) by the fiber; and finally subjecting the material to oxidation and finishing treatments to reconvert the dye to the insoluble form and fix it on the fiber, and further complete the finishing of the material.

The printing process of dyeing textile fabrics 5 generally involves applying a so-called printing paste to the fabric in the form of a design (for example by means of a screen, a stencil or an engraved roll), and then subjecting the printed fabric to further treatment to fix the 10 dye. In general, vat dye printing pastes contain, in addition to the unreduced vat dye, sub stances which in themselves do not reduce the vat dye under the conditions of the printing operation but which in the subsequent operations 5 (such as application of heat and/or steam) react with the dye to reconvert it to the soluble form (such as sodium formaldehyde-sulfoxylate and potassium carbonate), other substances or assistants which promote the reduction of the 20 dye and/or absorption of the reduced compound by the fiber, and suitable gums or thickeners. In some cases, as in printing with difficulty reducible vat dyes, the vat dye in the'printing paste is subjected to a preliminary partial reduc- 25 tion before applying the printing paste to the fabric. The fixing treatment usually comprises subjecting the printed fabric to a short treatment with wet steam while excluding air (socalled steaming or aging) whereby the vat 30 dye is reduced (for example, by the action of the sodium-formaldehyde-sulfoxylate and potassium carbonate), or its reduction is rendered more complete, and the reduced dye is taken up by the fiber, and then subjecting the fabric to oxi- 35 dizing, washingand other finishing-treatments. Vat dyes, when applied to fabrics by. a padding processor when printed on fabrics with the aid of alkalies, as for example alkali metal carbonates or alkali metal bicarbonates, frequently 40 fail to yield full color "value. This may be attributed to improper fixation of the dye on the fiber because of variable aging conditions or variable physical conditions of the vat dye padding liquors or printing paste. 45

of the vat dyes, especially of the indigoid and thioindigoid classes. Glycerine and the other 55 soluble polyhydric alcohols have the objection that their assisting action is limited, and further the amount which can be employed in vat dye printing pastes without objectionable marking ofi of the dyestuff due to improper drying and high hygroscopicity. Low boiling monohydric alcohols are objectionable in vat printing pastes, inasmuch as they evaporate prior to the aging step and even before application to the fiber, thus causing partial drying out of the paste and premature loss of assistant, resulting in uneven prints. A vat dye assistant, to be most effective, should be present during the reducing or aging step. The use of higher boiling monohydric alcohols has the objections that they are insufficiently soluble in water, and especially in printing pastes, to yield good homogeneity, and they impair the good working properties of vat dyestuff printing pastes. In general the assistants heretofore proposed further suffer from the fact that they produce little or no improvement in prints of light shades.

The use of dispersing agents has also been proposed in the dyeing with vat dyes by the pad-jig process, but they are open to the objection that they act mainly during the padding operation and do not assist in the absorption or adsorption of the leuco compound of the vat dye in the reducing or jigging step.

The present invention is based upon the discovery that the soluble salts of the acid reaction products resulting from the interaction of a polyhydric alcohol containing less than 6 carbon atoms with one or more molecular proportions of a polybasic inorganic acid or suitable derivative thereof possess a combination of properties which render them of particular value for use as assistants in the dyeing of textile fibers, and especially those of the vegetable type, such as cotton, rayon (regenerated cellulose) and the like, by a process in which a leuco compound of a vat dye is formed by reduction in the presence of the fiber to be dyed, and especially by pad-jig and printing processes, as well as in the preparation of printing pastes and padding liquors for dyeing textile fibers with vat dyes. Thus the soluble salts of the acid reaction products of sulfuric acid or chlorsulfonic acid upon the aliphatic polyhydric alcohols which contain 5 or less carbon atoms, which products are considered to be acid alkyl sulfates corresponding with the formula HOaSOROX (in which R is a hydrocarbon radical containing not more than 5 carbon atorris and X is H or SOsH), as well as others of the hereinafter described ester salts, have the faculty of rapidly entering into solution in water and other aqueous suspension media usually employed in dyeing with vat dyes. They furthermore have no tendency to cause the pastes to foam or lather. In addition they act asassistants in the absorption or adsorption of the reduced compounds of the vat dyes by the fiber, and in the penetration of woven fabric by the reduced compounds of the vat dyes during the developing, steaming or aging operations.

While most of the known vat dye printing assistants exert a very definite action, for example catalytic, dissolving, or enolyzing, on the vat dye, the ester salts of the present invention apparently act on both the vat dye and the fiber itself, causing more effective absorption of the leucocompound of the dyestufiand greatly increasing the printing strength of printing pastes.

Although I do not wish to be limited to any theory of reaction involved in using the assistants of the present invention, it is possible that the alkyl sulfates referred to are partially saponified by the alkaline reagents present in the printing paste so that during the aging operation these materials are slowly acted upon to liberate the corresponding polyhydric alcohol, and that therefore the alkyl sulfates behave not only as sulfates but as polyhydric alcohols, serving to more effectively dissolve or disperse the leuco form of the vat dyestuff. This is further borne out by the fact that other materials which are capable of saponification to produce free polyhydric alcohols, such as the acid alkyl phosphates, phosphites, borates and silicates, also yield improved results in pad-jig dyeing and printing with vat dyes.

The alkyl ester salts employed in accordance with the present invention comprise especially the soluble salts of the acid alkyl esters herein described, e. g., those resulting from the combination of any suitable metal or base, including the organic bases, with the said acid alkyl esters. It is particularly advantageous, however, to use the alkali metal salts of the acid alkyl sulfates and phosphates, or the salts formed by the interaction of the acid alkyl sulfates orphosphates with aliphatic or aromatic amines, for example, the alkylol amines. Thus the potassium and sodium salts of the said acid alkyl esters, or the salts of the acid alkyl esters with diethanolamine, triethanolamine, pyridine, or other saltforrning ammonium base, may be used. The sodium salts, in view of their extremely high solubility in water and alkaline printing pastes (which permits their incorporation into such printing pastes in almost any desired amount), are of especial value.

The said salts of alkyl esters employed in accordance with the present invention may be prepared in any manner well known to the art; as for example, by the treatment of the corresponding polyhydric alcohol in the presence or absence of a solvent or diluent, with a suitable inorganic reagent (such as phosphorus chloride or oxychloride, concentrated sulfuric acid and/or chlorsulfonic acid, etc.), and neutralization of the resulting acid alkyl ester with an inorganic or organic base which forms a readily soluble salt with said acid alkyl ester. It may be noted that the salts of alkyl monoand di-sulfuric acids resulting from the use of sulfuric acid or chlorsulfonic acid may contain varying amounts of salts of sulfonic acids which are sometimes produced due to secondary reactions; the presence of such sulfonic acid salts, however, does not impair the usefulness of the said salts of alkyl sulfuric acids in accordance with the present invention.

As illustrating acid alkyl esters, the soluble salts of which may be employed in accordance with the present invention, there may be mentioned the various acid alkyl esters which are derivatives of polyhydric alcohols containing not more than 5 carbon atoms; as for example, the monohydroxyalkyl sulfuric, boric and phosphoric acids containing not more than 5 carbon atoms (derived from glycerin or various glycols containing 5 or less carbon atoms); the monoalkyl, and monohydroxyalkyl, disulfuric and diphosphoric acids containing not more than 5 carbon atoms; the dialkyl, di (hydroxyalkyl'), and hydroxy alkyl-alkyl phosphoric and boric acids containing not more than 5 carbon atoms in the alkyl groups; etc. (such as, ethylene glycol monosulfuric acid, ethylene glycol disulfuric acid, ethylene glycol diphosphoric acid, glycerine disulfuric acid, glycerine mono-phosphoric acid, diglycerin boric acid, etc.).

It is to be noted, in the case of acid alkyl esters which are derivatives of polybasic acids containing 3 or more replaceable hydrogen atoms in which more than one of said hydrogen atoms have been replaced by organic radicals, the said organic radicals may be the same or different.

Mixtures of salts of the said acid alkyl esters also may be employed in accordance with the present invention. For example, the salts of suitable inorganic or organic bases with the mixtures of acid alkyl esters resulting from the sulfonation of the mixture of glycols obtained from mixed olefinic hydrocarbons formed in the production of gasoline by the so-called cracking process of petroleum distillation.

The percentage of assistant of the present invention that maybe employed is not critical and improved results are obtained with even as little'as 1 per cent or 2 per cent (based on the total weight of the printing paste or padding liquor).

The advantageous action of the said salts of the acid alkyl esters may be secured in a number of ways. Thus the said alkyl ester salts may be incorporated into the usual printing pastes or padding liquors. The said alkyl ester salts are in general crystalline products and hence may be added directly to the printing paste or padding liquor to cause the desired efiect. Further, the advantageous action may be secured by subjecting the cloth to be dyed or printed to a preliminary treatment with the solution of the said alkyl ester salt, as for example, impregnation. In copending application Serial No. 673,031, filed May 26, 1933, vat dye compositions in the form of powders are described containing vat dyestuffs and alkyl ester salts of the type herein disclosed. Such compositions,,in view of their content of said alkyl ester salts, may be employed in accordance with the present invention merely by mixing them with the usual thickener, alkali (potassium carbonate), reducing agent (sodium formaldehyde sulfoxylate), water and/or other usual ingredients of printing pastes, and employing them for printing in the ordinary manner.

The acid alkyl esters may also be employed as such in preparing printing pastes and padding liquors containing alkali inasmuch as the salts of said acid alkyl esters will be formed in the resulting compositions and there exert their advantageous action.

In dyeing by the printing process the printing paste may contain printing catalysts or boosters, reduction accelerators, hydrotropic and/or enolyzing substances, and the like.

The presence of enolyzing substances in vat dye printing pastes prepared in accordance with the present invention is'of particular advantage in connection with vat dyes of the indigoid and thioindigoid series, inasmuch as they tend to minimize or prevent isomerization of the reduced vat dye to the keto form. A

If desired, foam-breaking or foam-preventing agents may also be included in the compositions of the present invention in connection with vat dyes which have a tendency to produce foaming.

It is to be noted that under the term hydrotropic substances are to be understood not only the substances specifically enumerated by Neuberg and Tamba (compare Carl Neuberg, Biochemische Zeitschrift, vol. 76, 1916, page 107 ff and Tamba, Biochemische Zeitshrift, vol. 145, 1924, page 415; Carl Neuberg, Sitzungsberichte der gioengl. Preussischen Akademie der Wissenschaften, 1916, page 1034), but all of those substances, which comply with the definition of the word hydrotropic as given by Neuberg. As examples of such substances the following may be mentioned: urea, substituted ur'eas, thiourea, hexamethylene tetramine, the potassium salt of ethyl sulfonic acid, potassium or sodium isovalerate, the alkali metal salts of the following acids: isobutyric acid, phenylacetic acid, benzoic acid, o-toluene-carboxylic acid, salicyclic acid, the benzene sulfonic acids, p-toluene sulfonic acid, the benzene sulphinic acids, 1.4-toluene sulphinic acid, naphthalene sulfonic acids, aniline sulfonic acids and substitution products thereof, naphthylamine sulfonic acids (as for example, l-amino naphthalene-3.6.8-trisulfonic acid), picolinic acid, hydro aromatic carboxylic or sulfonic acids, and the like. It will be further noted that substances which are not, strictly speaking, hydrotropic substances but which possess enolyzing properties are included, as for example, 1- naphthalene sulfonic acid (sodium salt).

The invention may be employed in connection with vat dyes of all types including those derived from anthraquinone, indophenols, various indigoid, thioindigoid and indirubin compounds, etc.; as for example, indanthrones, pyranthrones, flavanthrones, dibenzanthrones, isodibenzanthrones, perylene quinones, anthanthrones, dibenzpyrene quinones, anthrimidocarbazols, naphthacridones, indigo, thioindigo, indirubin, etc., including 'derivatives thereof, such as their halogen, nitro, sulfur, and/or alkoxy derivatives. The term vat dye compound is intended to cover specifically the vat dye in the insoluble form and in the form of the free leuco compound or a soluble metal (or organic ammonium base) salt thereof (in the presence of alkaline compounds). Ordinarily a vat dye printing paste contains the vat dye in the insoluble form. It may also contain the vat dye in the leuco form either alone or in addition to the vat dye, as when the vat dye is prereduced.

Examples of vat dyestuffs with which the present invention may be employed are such indigoid and thioindigoid dyestufis as the following:

Color Index No. Color Index No. Color Index No. Color Index No. Color Index No. Color Index No. Color Index No.

National Vat Scarlet G National Vat Brown G (dinaphthyltlnoindigo) National Vet Violet R National Vat Pink (6,6'

methyl-2,2-bis-thio-naphthen-Indrgo) 1661B; 'Ii'diiff Color Index No. 1199 National Vat Pink BG Color Index No. 1210 National Vat Yellow G... Color Index N o. 1196 National Vat Yellow R Color Index No. 1170 And such anthraquinone vet dyes as the following: N ationel Garbanthrene Blue RS Color Index N o. 1106 N ational Cerbenthrene Blue 30 Color Index No. 1109 National Carbanthrene Blue GCD Color Index No. 1113 National Carbanthrene Yellow G Color Index No. 1118 National Carhanthrene Golden Orange 2R1- Color Index No. 1097 National Carbenthrene Golden Oran e G... Color Index No. 1006 National Cerbanthrene Blue Green FB. Color Index No. 1173 National Carbanthrene Violet 2R... Color Index No. 1104 National Carbanthrene Dark Blue DR Color Index No. 1099 National Carbanthrene Flevine GC Color Index N o. 1095 National Carbanthrene Red Violet 2RNX- Color Index N0."ll6l National Cerbanthrene Brilliant Green supra Color Index No. 1101 National Carbanthrene Green B. Color Index No. 1102 atlonal Carbanthrene Brown AR" Color Index No. 1151 National Carbanthrene Olive R Color Index No. 1150 National Cerbanthrene Red BN. Color Index No. 1162 National Carbanthtene Red AFF Color Index No. 1133 National Carbanthrene Black I Furthermore, mixtures of two or more vat dyes may be employed, for example when it is desired to produce compound shades such as scarlets, navy blues, blacks and browns,

Other assistants may be used together with theassistants of the present invention, as their effectiveness' is not impaired by the use of any of the usual assistants; for example, suitable monoor polyhydric alcohols (f. i., glycerine), hydroxyalkyl ethers, alkylol amines, etc.

The invention is not restricted to any particular method of applying the vat dyes but includes the dyeing of piece goods (cotton, rayon, etc.) by the pad-jig process and the printing of piece goods by the various printing processes (including discharge printing and color discharge printing as well as ordinary types of vat dye printing), in which various methods of applying the padding liquor or printing paste are employed.

The alkyl ester salts of the present invention yield especially beneficial results. .Because of their non-volatility, there is no danger of their evaporation prior to the aging process; hence the uniformity of the vat dye printing pastes is retained and a proper drying of the printed mate rial is secured. While formerly known assistants produce little or no improvement in prints of light shades, the compounds of the present invention are especially distinguished by the noticeable increase in printing strength obtainable by their use, even with very light shades. The alkyl ester salts of the present invention are particularly valuable in pad-jig dyeing and printing of so-called gray goods (unbleached cotton fabrics, raw regenerated cellulose fabrics and the like) with vat dyes, inasmuch as the dyeings and prints obtained with the aid of such alkyl ester salts have exceedingly high tinctorial value and excellent penetration as compared with dyeings and prints made in the absence of said alkyl ester salts.

The salts of the acid alkyl esters of the present invention are further of particular benefit in dyeing andprinting with vat dye compositions which contain heavy metal compounds as printing catalysts or boosters or reduction accelerators. It has heretofore been suggested to employ compounds of heavy metals (and metalloids) which are capable of exhibiting more than one valency, as for example, the salts (halides, su1- fates, acetates, etc.), oxides or hydroxides of iron, copper, tin, zinc, titanium, chromium, nickel, mercury, arsenic, etc. for this purpose. Many compounds of this type do not exhibit, however, the desired catalytic or boosting action when employed in the usual printing pastes. cordance with the present invention, such heavy metal compounds are employed in conjunction with the acid alkyl esters herein described, whereby an-eifective catalytic reducing action on the vat dyes is secured. Thus, when the alkyl ester salts herein described are employed in connection with heavy metal salts of said type exhibiting catalytic or boosting action when present, for example, in proportions of about 0.05

to about 3 per cent by weight of the vat dye printing pastes, an increase in the catalytic or boosting action of said heavy metal salts is obtained. Further, when the hereindescribed acid alkyl esters are employed in conjunction with heavy metal compounds of the said type not exhibiting catalytic or boosting action in the usual vat dyestuff printing pastes, catalytic or boosting" action is secured. This combined advantageous effect may be secured by employing the said heavy In ac- TEXTILE PRINTING A standard starch-tragacanth thickener is prepared by mixing together and boiling the following ingredients, any loss of water being replaced after boiling:

Parts Cornstarch 1 British gum 3 5% tragacanth solution 1 Water 5 Example 1 Part 1.'A stock printing thickener is made up by mixing 52 parts of the above standard starch-tragacanth thickener 15 parts of potassium carbonate (K2003) and 10 parts of water and heating until the potassium carbonate is completely dissolved, bringing the resulting paste to a temperature of 160 F., and adding 12 parts of sodium formaldehyde sulfoxylate,

and 11 parts of water.

Part 2.

20 parts of National Vat Orange R paste (containing about'13% of dye solids), parts of the stock printing thickener of Part 1, and 10 parts of disodium (or dipotassium) glycol disulfate are thoroughly mixed to insure a paste of uniform composition. The resulting vat dye printing paste is printed, for example by means of an engraved roll, upon a cotton fabric, the printed fabric is dried, and then subjected to'the aging action of air-free, saturated steam at 102 C. for 3 to 5 minutes. After this aging treatment the fabric is rinsed in a stream of cold water and is then soaped at boiling temperature in the presence of air until the dye is fully developed. The resulting printed fabric exhibits full penetration and a strength of print 15 to 20 per cent greater than is obtained by the same printing method and printing paste but with the glycol disulfate salt omitted.

The glycol disulfate salt may be prepared, for example, by adding 866 parts of chlorsulfonic acid to 232 parts of well-stirred ethylene glycol maintained at a temperature of about 15 to 30 0.; raising the temperature of the mixture to 45 to 50 C. and maintaining said temperature until the sulfation is complete; then cooling the mixture to about 15 C. and adding it to a well-stirred solution of 400 parts of sodium carbonate (or 523 parts of potassium carbonate) dissolved in 1500 parts of water to which 1500 parts of ice have been added; and recovering the disodium (or dipotassium) glycol disulfate in the form of a dry solid.

Prints of lighter shade may be obtained by using a printing thickener containing a considerably lower percentage of potassium carbonate and sodium formaldehyde sulfoxylate, for example by reducing the amounts of potassium carbonate and sodium formaldehyde sulfoxylate in the thickener of this example to about 7% potas sium carbonate and 5% sodium formaldehyde sulfoxylate.

Example 2 20 parts of National Vat Pink FF paste (containing 15% of dye solids),

68 parts of the stock printing thickener of Example 1, Part 1, and

12 parts of disodium glycerine monophosphate are intimately mixed to form a uniform printing paste. When printed and developed as in Example 1, the resulting prints are brighter and 20% stronger than those obtained without the addition of the disodium glycerin monophosphate.

Instead of the disodium glycerin monophosphate, the sodium salt of glycerin diphosphate may be employed. Furthermore, 0.1 to 0.5 part of ferrous sulfate (FeSOMHzO) or 0.1 to 0.5 part of nickel sulfate (NiSO4.7H20) or 1- part of nickel isobutyl borosulfate or of the iron, nickel, cobalt, manganese or chromium salts of glycol mono- (or di-) sulfuric acid, glycerin monophosphoric acid, etc., may be added per parts of printing paste to I catalyze the printing action of the vat dye.

Part 1.A printing thickener is prepared by mixing 52 parts of the above standard starch-traga canth thickener, 1'? parts of potassium carbonate, 7 14 parts of sodium'formaldehyde sulfoxylate,

5 parts of glycerin, and 12 parts of water.

Part 2.-A printing paste is formed by mixing .68 parts of the printing thickener of Part 1 with a 20 parts of National Carbanthrene Blue GCD dye paste (containing 17% of dye solids and 1% of leukanol) and 12 parts of a hereindescribed alkyl ester salt (for example, the sodium or potassium salt of glycerine disulfuric acid).

When this printing paste is printed upon a textile fabric as in Example 1 and the'print is dried, aged, oxidized, rinsed, soaped and finished in a similar manner, prints of increased strength are produced.

Prints of lighter shades may be obtained by cutting the printing paste, as given in Part 2 of the present example, with a paste for reductions obtained by reducing the quantity of potassium carbonate and sodium formaldehyde sulfoxylate in the printing thickener of thisexample, for example, to 8% and 6%, respectively, ofthe total printing thickener. The increased strength over prints obtained without the addition of the glycerine disulfate is especially noticeable with such lighter shades.

Pan-{Ira Drama Example 4 A padding liquor is prepared containing the following ingredients in the following approximate amounts:

National Carbanthrene Blue GCD in the form of the double paste (Color Index for example, by mixing the dyestufi paste with the glycol disulfate salt, which is'preferably employed in the form of an aqueous solution, adding the gum arabic and gum tragacanth in the form of an aqueous solution, bringing the total volume up to the said volume with additional water, and straining the mixture through a cloth of fine mesh. Cotton piece goods are padded or printed with the liquor in any suitable manner (for example, by passing the cloth between rolls through a'. vessel containing the padding liquor which is preferably at a temperature of about F.). The padded or printed cloth is then treated on the jig in the well-known manner, for example, in an alkaline hydro-sulfite bath preferably maintained at a temperature of. about to F., wherein the color rapidly develops, and is then finished in any convenient known way.

The dyeings thus obtained are of an increased brightness and fullness of shade and are better penetrated as compared with those obtained by the same process but with the employment of a padding liquor containing no glycol disulfate salt.

' sodium and potassium salts of the said acid alkyl sulfates and phosphates maybe used instead of the glycol disulfate salt. Similar improved dyeings may be obtained by replacing the vat dye paste and glycol disulfate salt of the present example by 30 grams of a vat dye powder produced in accordance with the process described in copending application Serial No. 673,031, filed May 26, 1933, and containing dipotassium glycol disulfate as a part thereof.

The action of the acid alkyl ester salts as penetrating agents and surface tension lowering agents may be enhanced by adding to the padding liquora small amount of caustic alkali, alkali metal carbonate, trisodium phosphate, sodium silicate, etc. For example, 1 to 3 parts of said substances may be added to the paste of this example.

As above indicated, the advantageous action of the salts of the acid alkyl esters as assistants in pad-jig dyeing and printing also may be seecured by pretreating the fiber with the salt of the acid alkyl ester. The following example illustrates such pretreatment.

Example 5 Bleached or unbleached cotton cloth is padded with a solution containing, for example, about 5 to about 30 parts per 1000 parts of water of disodium glycol disulfate or any of the other salts of acid alkyl esters herein described, for example by passing the cloth through the solution contained in a padding box equipped with squeeze rolls. Preferably, the padding liquor also contains about 2 to about 5 parts of gum tragacanth or other suitable thickener per 1000 parts of liquor. The pressure of the squeeze rolls is preferably so regulated that the cloth retains its own weight of the padding liquor. The padded cloth is then passed through a hot air drier or over hot cans, is rolled up and is then ready for printing or dyeing. The penetration obtained this way is superior, especially for lighter shades. This process is particularly suitable for artificial fibers of the regenerated cellulose type. If desired, alkalies, such as caustic alkalies, alkali metal carbonates, trisodium phosphate, etc. may also be added to the padding liquor.

This application is a continuation-in-part of application Serial No. 673,031, filed May 26, 1933.

I claim:

1. In the dyeing of textile fibers by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye compound, the improvement which comprises carrying out the dyeing with the aid of a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid and a polyhydric alcohol containing not more than 5 carbon atoms.

2. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye, the improvement which comprises carrying out absorption of the leuco compound by the fiber in the presence of a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid and a polyhydricalcohol containing not more than 5 carbon atoms.

3. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye, the improvement which comprises carrying out absorption of the leuco compound by the fiber in the presence of a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid which contains one of the radicals S02 and PO and a polyhydric alcohol which contains not more than 5 carbon atoms and not more than 3 hydroxyl groups.

4. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye, the improvement which comprises carrying out the dyeing in the presence of an alkali metal salt of an acid alkyl ester containing not more than 5 carbon atoms and derivable from a polybasic inorganic acid which contains one of the radicals S02 and PO and a polyhydric alcohol which contains not more than 5 carbon atoms and not more than 3 hydroxyl groups.

5. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of more than 5 carbon atoms and not more than 3 hydroxyl groups.

6. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye, the improvement which comprises applying to'the fiber a vat dye composition containing a vat dye in the unreduced form and a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group, and derivable from a polybasic inorganic acid and a polyhydric alcohol containing not more than 5 carbon atoms and not more than 3 hydroxyl groups.

7. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye, the improvement which comprises applying to the fiber a vat dye composition containing a vat dye in the unreduced form and a soluble salt of an acid alkyl ester having the formula HOSSOROX in which R represents an aliphatic hydrocarbon radical which contains not more than 5 carbon atoms and X is H or SOsH.

8. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye, the improvement which comprises applying to the fiber a vat dye composition containing a vat dye in the unreduced form and a soluble salt of a glycol disulfate containing not more than 5 carbon atoms.

' 9. In the dyeing of textile fabrics of the vegetable type by a printing process, the improvement which comprises applying to the textile fabric a printing paste containing a vat dye compound, an alkali, a reducing agent, a thickener and an alkali metal salt of an acid alkyl ester containing not more than 5 carbon atoms and derivable from a polybasic inorganic acid which contains one of the radicals S02 and PO and a polyhydric alcohol which contains not more than 5 carbon atoms and not more than 3 hydroxyl groups.

10. In the dyeing of textile fabric of the vegetable type by'a printing process, the improvement which comprises applying to the textile fabric a printing paste containing a vat dye in the unreduced form, a reducing agent, an alkali, and an alkali metal salt of a glycol disulfate containing not more than 5 carbon atoms.

11. In the dyeing of textile fabrics of the vegetable type by a printing process, theimprovement which comprises applying to the textile fabric a printing paste containing a vat dye in the unreduced form, a reducing agent, an alkali and dipotassium glycol disulfate.

12. In the dyeing of textile fibers of the vegetable type by the pad-jig process, the improvement which comprises padding the textile fiber with a padding liquor containing a vat dye in the unreduced form'and a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid which contains one of the radicals S02 and PO and a polyhydric alcohol which contains not more than 5 carbon atoms and not more than 3 hydroxyl groups.

13. In the dyeing of textile fabric of the vegetable type by the pad-jig process, the improvement which comprises padding the textile fabric with a padding liquor containing a vat dye in the unreduced form and a soluble salt of an acid alkyl ester having the formula HO3SOROX in which R represents an aliphatic hydrocarbon radical which contains not more than 5 carbon atoms and X is H or $03K.

14. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in thepresence of the fiber by reduction of a vat dye compound, the improvement which comprises treating the fiber to be dyed with a solution of a salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid and a polyhydric alcohol containing not more than 5 carbon atoms, and subjecting the treated fiber to the dyeing process.

15. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye compound, the improvement which comprises treating the fiber to be dyed with a solution of a salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid which contains one of the radicals S02 and PO and a polyhydric alcohol which contains not more than 5 carbon atoms and not more than 3 hydroxyl groups, and subjecting the treated fiber to the dyeing process.

16. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye compound, the improvement which comprises treating the fiber to be dyed with a solution of an alkali metal salt of a glycol disuliate containing not more than 5 carbon atoms, and subjecting the treated fiber to the dyeing process.

1'7. A vat dye paste for use in the dyeing of textile fibers, comprising a vat dye in the unreduced form, a thickener, water and a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid'and a polyhydric al- (:ohol containing not more than 5 carbon atoms.

18. A vat dye paste for use in the dyeing of textile fibers comprising a vat dye in the unreduced form, a thickener, water and a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid which contains one of the radicals S02 and PO and a polyhydric alcohol which contains not more than 5 carbon atoms and not more than 3 hydroxyl groups.

19. A vat dye paste for use in the dyeing of textile fibers comprising a vat dye in the unreduced form, a thickener, water and an alkali metal salt of a glycol disulfate containing not more than 5 carbon atoms.

20. A vat dye paste for use in the dyeing of textile fibers comprising a vat dye in the unreduced form, a thickener, water and dipotassium glycol disulfate.

21. In the dyeing of textile fibers by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye compound, the improvement which comprises carrying out the dyeing with the aid of a compound of a heavy metal capable of exhibiting more than one valency and a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid and a polyhydric alcohol containing not more than 5 carbon atoms.

22. In the dyeing of textile fibers by a process in which a leuco compound of a vat dye is formed in the presence of the'fiber by reduction of a vat dye compound, the improvement which comprises carrying out the dyeing with the aid of a salt'of one of the metals nickel, cobalt and manganese, and a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid and a polyhydric alcohol containing not more than 5 carbon atoms.

23. In the dyeing of textile fibers of the vegetable type by a process in which a leuco compound of a vat dye is formed in the presence of the fiber by reduction of a vat dye, the improvement which comprises applying to the fiber a vat dye composition containing a vat dye in the unreduced form and a soluble salt of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group, and derivable from a polybasic inorganic acid and a polyhydric alcohol containing not more than 5 carbon atoms and not more than 3 hydroxyl groups, and a salt of a heavy metal capable of exhibiting more than one valency.

24. In the dyeing of textile fibers by a process in which a leuco compound of a vat dye is formed inthe presence of the fiber by reduction of a vat dye compound, the improvement which comprises carrying out the dyeing with the aid of a compound of a heavy metal capable of exhibiting more than one valency andof a soluble salt 'of an acid alkyl ester containing not more than 5 carbon atoms in the alkyl group and derivable from a polybasic inorganic acid which contains one of the radicals S02 and P and a polyhydric alcohol which contains not more than carbon atoms and not more than 3 hydroxyl groups 7 v 25. In the dyeing of textile fabrics by a printing process, the improvement which comprises applying to the textile fabric a printing paste containing a vat dye in the unreduced form,'an alkali, a reducing agent, a thickener, an alkali metal salt of an acid sulfate of a polyhydric alcohol containing not more than 5 carbon atoms, and a sulfate of a heavy metal capable of exhibiting more than one valency.

26. In the dyeing of textile fabrics by a printing process, the improvement which comprises applying to the textile fabric a printing paste containing a vat dye in the unreduced form, a salt of one of the metals nickel, cobalt and manganese,

and an alkali metal salt of an acid alkyl ester containing not more than 5 carbon atoms and derivable from a polybasic inorganic acid which contains one of the radicals SO: and PO and a polyhydric alcohol which contains not more than 5 carbon atoms and not more than 3 hydroxyl groups.

27. In the dyeing'of textile fabrics by a printing process, the improvement which comprises applying to the textile fabric a printing paste containing a vat dye in the unreduced form, a salt of one of the metals nickel, cobalt and manganese, and an alkali metal salt of a glycol disulfate containing not more than 5 carbon atoms.

JEAN G. KERN. 

